EP0377510A2 - Circuit de compensation de facteur de puissance - Google Patents

Circuit de compensation de facteur de puissance Download PDF

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Publication number
EP0377510A2
EP0377510A2 EP90300095A EP90300095A EP0377510A2 EP 0377510 A2 EP0377510 A2 EP 0377510A2 EP 90300095 A EP90300095 A EP 90300095A EP 90300095 A EP90300095 A EP 90300095A EP 0377510 A2 EP0377510 A2 EP 0377510A2
Authority
EP
European Patent Office
Prior art keywords
capacitor
voltage
circuit
power factor
filter capacitor
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
EP90300095A
Other languages
German (de)
English (en)
Other versions
EP0377510A3 (fr
Inventor
Joseph Christopher Borowiec
Sayed-Amr El-Hamamsy
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
General Electric Co
Original Assignee
General Electric Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by General Electric Co filed Critical General Electric Co
Publication of EP0377510A2 publication Critical patent/EP0377510A2/fr
Publication of EP0377510A3 publication Critical patent/EP0377510A3/fr
Ceased legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/42—Circuits or arrangements for compensating for or adjusting power factor in converters or inverters
    • H02M1/4208—Arrangements for improving power factor of AC input
    • H02M1/425—Arrangements for improving power factor of AC input using a single converter stage both for correction of AC input power factor and generation of a high frequency AC output voltage
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B41/00—Circuit arrangements or apparatus for igniting or operating discharge lamps
    • H05B41/14—Circuit arrangements
    • H05B41/26—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc
    • H05B41/28—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc using static converters
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/42—Circuits or arrangements for compensating for or adjusting power factor in converters or inverters
    • H02M1/4208—Arrangements for improving power factor of AC input
    • H02M1/4275—Arrangements for improving power factor of AC input by adding an auxiliary output voltage in series to the input
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
    • Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Definitions

  • the present invention relates generally to power circuits for obtaining a high power factor electronically.
  • this invention relates to a power factor correction circuit for use in an electronic ballast for gas discharge lamps which pre-charges the energy-storage or filter capacitor before the circuit oscillates, thereby avoiding destructive inrush current through circuit devices.
  • the power factor of a system is defined as real input power divided by apparent input power. Apparent power is calculated by multiplying root mean square (RMS) voltage and RMS current. Therefore, a system with a lower power factor requires larger input currents for a given real power than a system with a higher power factor.
  • RMS root mean square
  • Electronic circuits such as gas discharge lamp ballasts, generally operate from DC voltages. Hence, a means for converting AC line voltage to DC line voltage is required.
  • a conventional way to obtain a DC voltage from an alternating voltage source is through rectification and capacitive filtering.
  • the power factor which depends upon the value of the filter capacitor and the size of the load, is often too low. Therefore, the input current necessary to support input power is very high and can exceed the ratings of conductors and circuit breakers.
  • ballasts for gas discharge lamps include bulky low-frequency transformers and inductors and large power factor correction capacitors.
  • the inductors and transformers are necessary to limit the current in the lamps once they are ignited. This is due to the negative impedance characteristic of gas discharge lamps; that is, once the arc of a discharge lamp has been ignited, the current through the discharge medium increases, while the voltage drop between the lamp electrodes decreases. Therefore, an electromagnetic ballast acts as an inductive load, and a large power factor correction capacitor is used to increase the power factor.
  • the load presented by electronic ballasts to the AC line is capacitive. This is due, in part, to the above-described filter capacitors.
  • smaller transformers and inductors are used because electronic ballasts operate at higher frequencies, i.e. 20-50 kHz.
  • a power factor correction circuit is needed to correct for a capacitive load at high frequency operation.
  • a preferred embodiment of a power factor correction circuit for obtaining a high power factor electronically comprises a metal oxide varistor in series with a filter or energy-storage capacitor.
  • the varistor provides a low-impedance path for pre-charging the capacitor to a pre-selected fixed voltage level before the circuit oscillates. Once the capacitor is pre-charged, the varistor becomes an essentially non-conductive path, except when transients occur.
  • a power factor correction transformer maintains the charge across the capacitor. Thereafter, when the AC source voltage goes below the rectified line voltage, a coasting device means becomes conductive to enable the capacitor to discharge current to a load. During the time for which the capacitor is being charged by the power factor correction transformer, the load is energized by a fully rectified line voltage.
  • the varistor provides transient protection by effectively placing the capacitor across the line to absorb high voltage transients.
  • a further advantage results from the fact that the presence of the varistor decreases the voltage level across the filter capacitor. The reason is that the varistor can maintain a voltage drop up to the value of its breakdown voltage. Hence, a capacitor with a lower voltage rating may be used without affecting reliability of the circuit.
  • FIG. 1 An exemplary conventional rectification circuit is illustrated in Figure 1 which includes an AC source 10 connected across a full-wave diode bridge rectifier 12, and a filter capacitor C1 in parallel with a load 11 connected to the bridge output terminals.
  • a DC voltage across load 11 is obtained by supplying voltage from AC source 10 to full-wave diode bridge rectifier 12 and smoothing the DC voltage by operation of filter capacitor C1.
  • the power factor of such a circuit is generally too low for many applications, such as gas discharge lamp ballast circuits.
  • FIG. 2 A “bucket brigade” approach to power factor correction, which is known in the prior art, is illustrated in Figure 2.
  • this circuit includes AC source 10 connected across full-wave diode bridge rectifier 12 and filter capacitor C1.
  • the load in the circuit of Figure 2 comprises a gas discharge lamp 14 and power electronics 16.
  • dashed lines 18 enclose a typical ballast circuit.
  • power electronics 16 may include switching devices, control logic, high-frequency inductors and transformers, capacitors and/or other circuitry necessary for the operation of a gas discharge lamp.
  • Figure 2 also includes a series-connected capacitor C2 and secondary winding of a transformer 20 connected across filter capacitor C1.
  • the primary winding of transformer 20 is coupled to power electronics 16.
  • One end of capacitor C2 is driven by an alternating high frequency voltage supplied to transformer 20 by the power electronics so that the voltage on the other end of capacitor C2 is alternately higher and lower than the AC line voltage, V LINE .
  • V LINE AC line voltage
  • capacitor C2 discharges to filter capacitor C1 and to gas discharge lamp 14 via the power electronics.
  • the sum of these voltages is less than V LINE , current flows from the line to capacitor C2 through diode bridge rectifier 12 to the lamp. The result is an increased diode bridge conduction angle and, therefore, an increased power factor.
  • conduction angle is defined as the angle per 360 degrees for which a diode pair of bridge rectifier 12 conducts during a 60 Hz cycle.
  • the input signal from the power electronics to the transformer is complex, and high frequency filtering (not shown) of this signal is required. The result is a complex and costly scheme for raising power factor.
  • Another conventional power factor correction method differs from that shown in Figure 1 by using one or more external inductors 22 at the input to rectifier 12, as shown in Figure 3. Although power factor is increased, the inductor(s) required is bulky and expensive.
  • FIG. 4 is an illustration of a power factor correction circuit according to DE-A-3917850.1.
  • AC power supply 10 drives a conventional full-wave diode bridge rectifier 12, the output terminals of which are connected across series-­connected diode D1 and filter capacitor C1.
  • Diode D1 is therefore reverse biased as long as the rectified line voltage is greater than the voltage across capacitor C1.
  • charge from capacitor C1 through diode D1 supplies gas discharge lamp 14 via power electronics 16.
  • This arrangement effectively increases the conduction angle of the bridge rectifier to 120 degrees which, in turn, raises the power factor of the system to a value above 0.9.
  • high inrush current is avoided through circuit devices comprising power electronics 16 by the controlled charging and discharging of filter capacitor C1.
  • FIG. 5 An alternative method for controlling the charge of a filter capacitor to avoid high inrush current in an electronic ballast is by using a bootstrap circuit, such as the one illustrated in Figure 5.
  • This circuit differs from that of Figure 4 in that it employs a transistor T1 having a collector load resistor R2. Capacitor C1 is pre-charged through resistor R2 and transistor T1. The base of transistor T1 is coupled to the line by a bias resistor R1. A Zener diode D3 is provided to maintain the base voltage of the transistor at some predetermined level above ground, thus improving circuit efficiency by turning off the transistor and hence the bootstrap circuit once the voltage across capacitor C1 exceeds the Zener diode breakdown voltage. Once transistor T1 is off, the capacitor becomes charged by power factor correction transformer 20 through diode D2.
  • Diode D1 is reverse biased as long as the rectified line voltage is greater than the voltage across capacitor C1.
  • charge from capacitor C1 through diode D1 supplies gas discharge lamp 14 via power electronics 16.
  • the conduction angle of diode bridge rectifier 12 is effectively increased to 120 degrees, and the power factor of the system is greater than 0.9.
  • transistor T1 must be able to withstand high inrush currents and must likewise have a high breakdown voltage.
  • Figure 6 illustrates one embodiment of the power factor correction circuit of the present invention.
  • the circuitry of Figure 4 is improved by connecting in parallel with diode D1 a varistor 24.
  • varistor 24 comprises a metal oxide varistor (MOV) because of the MOV's fast response time and ability to withstand high voltage transients.
  • MOV metal oxide varistor
  • a metal oxide varistor is a two-terminal metal oxide semiconductor device having a voltage-dependent, non­linear resistance. When the voltage across the MOV is less than its breakdown voltage, the MOV has a high impedance value. In contrast, when the MOV breakdown voltage is exceeded, the MOV becomes a low impedance.
  • varistor 24 provides a low-impedance path for pre-charging capacitor C1. That is, as long as the input voltage V LINE from the line is greater than the sum of the varistor breakdown voltage and the voltage across the filter capacitor, diode D1 is reverse biased and varistor 24 provides a low-impedance path for pre-charging the capacitor.
  • the capacitor charge is maintained by a power factor correction transformer 20 through diode D2.
  • the power factor correction transformer is energized through power electronics 16. Thereafter, whenever the instantaneous AC source voltage goes sufficiently below the rectified line voltage V LINE , charge from capacitor C1 through diode D1 supplies the gas discharge lamp via power electronics 16. At all other times, the power electronics and the lamp are energized directly from the fully rectified voltage V LINE .
  • filter capacitor C1 After filter capacitor C1 is initially pre-charged, it is no longer charged through varistor 24 unless voltage V LINE exceeds the sum of the varistor breakdown voltage and the capacitor voltage. This occurs in the presence of a voltage transient at which time the MOV effectively acts as a short circuit that connects the capacitor across the line to absorb the transient, thus protecting devices of the circuit from the transients.
  • FIG. 7 An alternate embodiment of a power factor correction circuit in accordance with the present invention is illustrated in Figure 7. This embodiment differs from that shown in Figure 6 by employing a series combination of a Zener diode 26 and a resistor R3 in parallel with filter capacitor C1. As shown, the voltage signal at the cathode of the Zener diode is used to supply control logic 40 instead of voltage V LINE . This provides an efficient means of providing a logic level voltage source to control logic 40 because use of the varistor results in a decreased voltage level across the capacitor than if the varistor were not otherwise being employed, thus resulting in a higher efficiency ballast circuit for the gas discharge lamp.
  • FIG 8 illustrates another alternate embodiment of the present invention employed in a ballast circuit for driving two fluorescent lamps 50a and 50b.
  • AC power supply 10 drives full-wave diode bridge rectifier 12 which is connected across series-connected diode D1 and filter capacitor C1.
  • capacitor C1 is pre-charged through varistor 24 to a pre-selected fixed voltage level.
  • power factor correction transformer 20 charges capacitor C1 through diode D2 to half the value of the rectified line voltage, V LINE .
  • Diode D1 is therefore reverse biased as long as the rectified line voltage is greater than the voltage across C1.
  • charge from capacitor C1 supplies the power circuit through diode D1 at a voltage level equal to 1/2 V LINE .
  • control 40 drives converting transistors T2 and T3, connected in a half bridge configuration, at a start up frequency until the lamps ignite and at an operating frequency thereafter.
  • Capacitors C3 and C4 are the converter half bridge capacitors for transistors T2 and T3, respectively.
  • Control 40 may be implemented by any number of circuits well-known in the art for controlling half bridge resonant circuits.
  • One possible embodiment of control 40 is illustrated in commonly assigned U.S. Patent 4,672,528 of Park et al., which is hereby incorporated by reference. Although the circuit described in that patent is designed to control a full bridge connection of transistors, it may be suitably modified by one skilled in the art to control the half bridge circuit of Figure 8.
  • Transistors T2 and T3 convert the rectified DC voltage (V LINE ) to an AC voltage at a frequency determined by control 40.
  • Isolation transformer 42 enables control 40 to drive both legs of the converter since transistor T2 is floating with respect to the control ground.
  • Primary winding 44 of an isolation transformer 46 is connected between nodes a and b of the DC-to-AC converter.
  • Primary winding 44 drives secondary windings 48a and 48b in an isolated series configuration.
  • Capacitors C9 and C10 connected across lamps 50a and 50b, respectively, are selected to maximize the voltage across lamps 50a and 50b, respectively, at the start up frequency.
  • a series combination of a Zener diode 26 and a resistor R3 is connected in parallel with filter capacitor C1.
  • the voltage signal at the cathode of Zener diode 26 is the input signal to control 40 in order to improve the efficiency of the circuit.
  • the preferred embodiments of the invention described hereinabove provide a power factor correction circuit in which a filter capacitor is pre-charged before the circuit oscillates, thus avoiding high inrush currents through circuit devices; and/or a power factor correction circuit requiring a lower filter capacitor voltage level, thus enabling the use of a smaller filter capacitor, while achieving a high power factor without a significant ripple voltage; and/or a power factor correction circuit having transient protection capability.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Rectifiers (AREA)
  • Circuit Arrangements For Discharge Lamps (AREA)
EP19900300095 1989-01-05 1990-01-04 Circuit de compensation de facteur de puissance Ceased EP0377510A3 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US07/295,624 US5012161A (en) 1989-01-05 1989-01-05 Power factor correction circuit
US295624 1994-08-24

Publications (2)

Publication Number Publication Date
EP0377510A2 true EP0377510A2 (fr) 1990-07-11
EP0377510A3 EP0377510A3 (fr) 1991-10-09

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Family Applications (1)

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EP19900300095 Ceased EP0377510A3 (fr) 1989-01-05 1990-01-04 Circuit de compensation de facteur de puissance

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US (1) US5012161A (fr)
EP (1) EP0377510A3 (fr)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0618753A2 (fr) * 1993-03-29 1994-10-05 Ultra-Lum, Inc. Ballast électronique pour des appareils d'éclairage par transmission et de réticulation
FR2742010A1 (fr) * 1995-11-30 1997-06-06 Sgs Thomson Microelectronics Dispositif d'amelioration du facteur de puissance d'une alimentation redressee
EP1504635A1 (fr) * 2002-05-14 2005-02-09 Aurora Lighting, Inc. Ballast electronique pour lampes a decharge
EP3793078A4 (fr) * 2018-05-10 2022-01-19 Kabushiki Kaisha Toshiba Système de transformation de courant continu
EP3965276A1 (fr) * 2020-09-03 2022-03-09 Delta Electronics, Inc. Circuit de filtre à compensation d'harmonique

Families Citing this family (17)

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Publication number Priority date Publication date Assignee Title
US5977721A (en) * 1983-02-22 1999-11-02 Nilssen; Ole K. Controlled power-factor-corrected ballast
US5148359A (en) * 1991-12-23 1992-09-15 Gte Products Corporation Network for obtaining high power and low total harmonic distortion
US5148360A (en) * 1992-01-29 1992-09-15 Gte Products Corporation Fourth order damped lowpass filter for obtaining high power factor and low total harmonic distortion
US5471117A (en) * 1994-05-11 1995-11-28 Mti International, Inc. Low power unity power factor ballast
SE9401870L (sv) * 1994-05-31 1995-12-01 Ericsson Telefon Ab L M Anordning för omvandling av en växelspänning till likspänning
US5481161A (en) * 1995-02-10 1996-01-02 General Electric Company Variable frequency generator for resonant power feedback
US5517086A (en) * 1995-03-13 1996-05-14 General Electric Company Modified valley fill high power factor correction ballast
US5703438A (en) * 1996-01-22 1997-12-30 Valmont Industries, Inc. Line current filter for less than 10% total harmonic distortion
US5661645A (en) 1996-06-27 1997-08-26 Hochstein; Peter A. Power supply for light emitting diode array
US5872430A (en) * 1996-08-14 1999-02-16 Motorola Inc. Single switch electronic ballast with low in-rush current
GB9703088D0 (en) * 1997-02-14 1997-04-02 Switched Reluctance Drives Ltd Power supply circuit for a control circuit
US6150771A (en) * 1997-06-11 2000-11-21 Precision Solar Controls Inc. Circuit for interfacing between a conventional traffic signal conflict monitor and light emitting diodes replacing a conventional incandescent bulb in the signal
US5986558A (en) * 1998-05-29 1999-11-16 Marconi Communications, Inc. Modular precharge circuit
US6862201B2 (en) 2000-12-27 2005-03-01 Delta Energy Systems (Switzerland) Ag Method and circuitry for active inrush current limiter and power factor control
US6611169B2 (en) 2001-10-01 2003-08-26 Gibson Guitar Corp. Power supply regulation and protection circuit for audio power amplifier
US20090115257A1 (en) * 2007-11-02 2009-05-07 William Robert Letourneau Switchboard apparatus and method
US20100010924A1 (en) * 2008-07-14 2010-01-14 Green Equity, LLC Energy credit harvesting

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JPS5851322A (ja) * 1981-09-22 1983-03-26 Kansai Electric Power Co Inc:The 静止形無効電力補償装置
US4564897A (en) * 1983-01-13 1986-01-14 Matsushita Electric Works, Ltd. Power source
SU1288818A1 (ru) * 1985-02-01 1987-02-07 Казанский филиал Московского энергетического института Устройство дл регулировани мощности трехфазной конденсаторной батареи
US4949234A (en) * 1989-04-17 1990-08-14 Zdzislaw Gulczynski High efficiency power factor correction circuit

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US4109307A (en) * 1977-05-04 1978-08-22 Gte Sylvania Incorporated High power factor conversion circuitry
DE3524266A1 (de) * 1985-07-06 1987-01-08 Philips Patentverwaltung Schaltungsanordnung zum betrieb von hochdruckgasentladungslampen
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US4672528A (en) * 1986-05-27 1987-06-09 General Electric Company Resonant inverter with improved control
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JPS57132766A (en) * 1981-02-07 1982-08-17 Ikeda Denki Kk Dc power source circuit
JPS5851322A (ja) * 1981-09-22 1983-03-26 Kansai Electric Power Co Inc:The 静止形無効電力補償装置
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SU1288818A1 (ru) * 1985-02-01 1987-02-07 Казанский филиал Московского энергетического института Устройство дл регулировани мощности трехфазной конденсаторной батареи
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PATENT ABSTRACTS OF JAPAN, vol. 6, no. 230 (E-142)[1108], 16th November 1982; & JP-A-57 132 766 (IKEDA DENKI K.K.) 17-08-1982 *
PATENT ABSTRACTS OF JAPAN, vol. 7, no. 134 (P-203)[1279], 11th June 1983; & JP-A-58 51 322 (KANSAI DENRIYOKU K.K.) 26-03-1983 *
PROCEEDINGS OF THE 10TH INTERNATIONAL PCI, October 1985, pages 19-32; J.J. SPANGLER: "A power factor corrected, MOSFET multiple output, flyback switching supply" *
SOVIET INVENTIONS ILLUSTRATED, week 8738, 30th September 1987, section Electronics, abstract no. 87-269880/38 X12, Derwent Publications Ltd, London, GB; & SU-A-1288 818 (KAZAN MOSC POWER) 07-02-1987 *

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0618753A2 (fr) * 1993-03-29 1994-10-05 Ultra-Lum, Inc. Ballast électronique pour des appareils d'éclairage par transmission et de réticulation
EP0618753A3 (en) * 1993-03-29 1995-11-29 Ultra Lum Inc Electronic ballast for transilluminators and crosslinkers.
FR2742010A1 (fr) * 1995-11-30 1997-06-06 Sgs Thomson Microelectronics Dispositif d'amelioration du facteur de puissance d'une alimentation redressee
EP1504635A1 (fr) * 2002-05-14 2005-02-09 Aurora Lighting, Inc. Ballast electronique pour lampes a decharge
EP1504635A4 (fr) * 2002-05-14 2005-05-25 Aurora Lighting Inc Ballast electronique pour lampes a decharge
US7129647B2 (en) 2002-05-14 2006-10-31 Aurora Lighting, Inc. Electronic ballast with programmable processor
EP3793078A4 (fr) * 2018-05-10 2022-01-19 Kabushiki Kaisha Toshiba Système de transformation de courant continu
US11664737B2 (en) 2018-05-10 2023-05-30 Kabushiki Kaisha Toshiba DC transformation system
EP3965276A1 (fr) * 2020-09-03 2022-03-09 Delta Electronics, Inc. Circuit de filtre à compensation d'harmonique

Also Published As

Publication number Publication date
EP0377510A3 (fr) 1991-10-09
US5012161A (en) 1991-04-30

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